There’s a WER update today, it’s made local player databases inaccessible for many people. Let your local store know to backup their local player database before doing any updates (click no when it asks if you want to update), and to leave the update until after it’s fixed.
Also before even opening WER you can go to
C:\Users\User\AppData\Roaming\Wizards of the Coast\Event Reporter
and copy TournamentData.dat, email it to yourself in case of the worst case scenario.
If you’re affected downloading a fresh copy from the WPN site should work.
Thanks to Josh Silvestri and Mark Brown for quick investigation and fixes.